There are 717 words like that in the Scrabble dictionary. I trust that 157 examples of the more common ones will be sufficient:
acuity
acumen
alumna
alumni
amulet
bauble
bluing
bluish
blurry
bought
bounce
bouncy
bounds
bounty
bruise
brunch
brunet
brutal
caucus
caudal
caught
causal
chubby
chummy
chunky
church
clumsy
clutch
cougar
county
couple
coupon
course
cousin
cruddy
cruise
crumby
crummy
crunch
crusty
crutch
double
doubly
douche
doughy
dourly
drudge
equate
equine
equity
faucet
faulty
feudal
fluent
fluffy
flunky
flurry
fought
foully
fourth
frugal
fruity
frumpy
gauche
gaucho
glumly
gluten
gouger
grubby
grudge
grumpy
grunge
grungy
haunch
hourly
iguana
jaunty
jounce
klutzy
launch
laurel
loudly
lounge
louver
mouser
mousse
muumuu
naught
nausea
neural
neuron
neuter
nougat
nought
ocular
paunch
pauper
plucky
plunge
plural
plushy
pounce
saucer
sculpt
scummy
scurry
scurvy
scuzzy
shucks
sludge
sluice
slushy
smudge
smudgy
smugly
smutty
snugly
sought
source
sourly
spunky
sputum
squall
square
squash
squawk
squeak
squeal
squint
squire
squirm
squirt
squish
stubby
stucco
studio
stuffy
stumpy
stupid
stupor
sturdy
taught
Taurus
tautly
toucan
touche
touchy
toupee
tousle
truant
trudge
truism
trunks
trusty
unused
usurer
uvular
Some 6 letter words with U as the third letter:abusedblurrybountybrunchblurtsboundschumpschurchcountycourtschurnscrustychummycrummychuckscrunchdrunksflurryfluentfourthgruntshourlymournsmoundspouredpoundsroundsscurrysoundsslurpssouredspurnssturdyshucksstuntsskunksstumpsscummytouredtruststrumpstrunkstruant
Some five letter words with U in the middle are:abuseazurebluntblurbblushbrushchurnchumpclumpcrushdauntdoubtdruidfluidfruitgourdgrumpgrunthaunthoundhousejoustlousemauvemousemouthplushpoundroughroundroutesaucesautesoundsouthtouchvouchyouth
Some seven letter words with the second letter A and the third letter U are:bauxitecausticcautiondauphinhaughtyhauntedhauteurlaundrymaudlinnaughtypaunchyraucousraunchysauntersausagevaulted
Some 8 letter words with U as the 3rd letter:AbundantAdulteryAluminumAquanautAquariumAquaticsAquatintAqueductAquifersAquilineBaulkingBlubbersBlubberyBludgeonBluebellBluebirdBluffingBlundersBluntestBluntingBlurrierBlurringBlurtingBlushingBouffantBouillonBouldersBouncersBouncierBouncilyBouncingBoundaryBoundingBountiesBouquetsBourbonsBoutiqueBruisingBrunchedBrunchesBrunetteBrushingBrushoffBrutallyCauldronCaulkingCausallyCausewayCautiousChubbierChuckledChucklesChuggingChummierChummilyChunkierChurchesChurningClubbingClubroomCluckingCluelessClumpierClumpingClumsierClumsilyClustersClutchedClutchesCluttersCoughingCouncilsCounselsCountersCountessCountiesCountingCoupletsCouplingCouriersCourtesyCourtingCrucifixCruelestCruisersCruisingCrumbledCrumblesCrumpledCrumplesCrunchedCrunchesCrusaderCrusadesCrushingCrustierDaughterDauntingDiureticDoublingDoubtersDoubtfulDoubtingDoughierDoughnutDrudgingDrummersDrummingDrunkardDrunkest
buttcutecutsgutshutsjutejutsmutemuttnutsputsruts
Some 6 letter words with U as the third letter:abusedblurrybountybrunchblurtsboundschumpschurchcountycourtschurnscrustychummycrummychuckscrunchdrunksflurryfluentfourthgruntshourlymournsmoundspouredpoundsroundsscurrysoundsslurpssouredspurnssturdyshucksstuntsskunksstumpsscummytouredtruststrumpstrunkstruant
I could only find one: whumps
Some five letter words with U in the middle are:abuseazurebluntblurbblushbrushchurnchumpclumpcrushdauntdoubtdruidfluidfruitgourdgrumpgrunthaunthoundhousejoustlousemauvemousemouthplushpoundroughroundroutesaucesautesoundsouthtouchvouchyouth
Some seven letter words with the second letter A and the third letter U are:bauxitecausticcautiondauphinhaughtyhauntedhauteurlaundrymaudlinnaughtypaunchyraucousraunchysauntersausagevaulted
Some 8 letter words with U as the 3rd letter:AbundantAdulteryAluminumAquanautAquariumAquaticsAquatintAqueductAquifersAquilineBaulkingBlubbersBlubberyBludgeonBluebellBluebirdBluffingBlundersBluntestBluntingBlurrierBlurringBlurtingBlushingBouffantBouillonBouldersBouncersBouncierBouncilyBouncingBoundaryBoundingBountiesBouquetsBourbonsBoutiqueBruisingBrunchedBrunchesBrunetteBrushingBrushoffBrutallyCauldronCaulkingCausallyCausewayCautiousChubbierChuckledChucklesChuggingChummierChummilyChunkierChurchesChurningClubbingClubroomCluckingCluelessClumpierClumpingClumsierClumsilyClustersClutchedClutchesCluttersCoughingCouncilsCounselsCountersCountessCountiesCountingCoupletsCouplingCouriersCourtesyCourtingCrucifixCruelestCruisersCruisingCrumbledCrumblesCrumpledCrumplesCrunchedCrunchesCrusaderCrusadesCrushingCrustierDaughterDauntingDiureticDoublingDoubtersDoubtfulDoubtingDoughierDoughnutDrudgingDrummersDrummingDrunkardDrunkest
Square ... although the third letter is 'u'
blurryblurtschurchchurnsflurryfourthhourlymournspouredscurryslurpssouredspurnssturdytoured
buttcutecutsgutshutsjutejutsmutemuttnutsputsruts
Haul and laud are four letter words. The 2nd letter is a. The 3rd letter is u.
Some six letter words that include the letter U are:absurdactualaroundauthorblouseblurryburdenburrowcampuschorusquaverstupidtruant
Aquatic, bluejay, clutter, elusion, flubber and journal are 7 letter words. The letter u is the 3rd letter.
Some six letter words ending in U are:bureaugateaulandaumilieumuumuu