The /u/ vowel is spelled <oo>, <ew>, <u> and <o> in who. The /ɪə/ diphthong is spelled <eerCe> or <ear> and <eir> in weird.
This is a contrast between a long vowel and a diphthong, widely separated in starting position and distinguished by lip-rounding. It is not a problem for any learners.
The density figure is 1.31%. The set makes 32 semantic contrasts giving a loading of 60.4%.
boo beer boos beers boo bier boos biers booze beers booze biers booed beard chew cheer chews cheers chewed cheered clew clear clewed cleared clews clears clue clear clues clears clued cleared do dear do's dears do deer do's deers food feared gnu near gnus nears Jew jeer Jews jeers loon lien loons liens lieu leer loo leer loos leers moo mere moos meres ooze ears rood reared rue rhea rues rheas ruse rheas rule real shoe shear shoes shears shoe sheer shoo shear shoos shears shooed sheared snood sneered snooze sneers too tear two tear twos tears who's hears woo weir woos weirs wooed weird
John Higgins, Shaftesbury, December 2009