The /ʊə/ sound is spelled with <u> or <ur>.
As /ʊə/ is fairly rare, only occurring in 1053 words in the dictionary, this was a fairly easy list to work out manually. Since the diphthong is often preceded by a palatal semivowel /j/, there turned out to be very few pairing words when one deleted it. For example, in the pairs annuals/annals and furies/frizz, I have actually deleted /jʊə/ rather than /ʊə/, but I left these pairs in as they seemed interesting.
The density value and semantic loading are irrelevant with such a small and contentious list.
annuals annals furies frizz touring Tring Urdu do
John Higgins, Shaftesbury, December 2010.