The pronunciation of housewife is complicated. According to OED 1 two forms of compounds with hus existed in ME, one with and one without a connective /e/, thus: husbond, husebond (OED 1 is unsure why). In the following couple of centuries, the two forms husewif and huswif diverged further in pronunciation:
That without the /e/ elided the /w/ and shortened the vowel in the initial syllable, which developed regularly into /ʌ/; the second syllable was destressed (the ordinary English pattern) and consequently shortened the vowel, yielding such orthographic forms as hussif, hussive and huzzy, which was until recently the ordinary pronunciation for the primary sense of “mistress of the house”.
that with the /e/ maintained the long first syllable and the /w/, and then developed regularly into /haʊswaɪf/, with two long vowels, reflected in the modern spelling. According to OED 1, this pronunciation was literary and dialectal into the 18th century, used only of transferred senses; but
the analytical form with long vowel, hūsewīf, hūswīf, houswif, housewife, continued in use and became frequent in Sense 1 in the 16th c., esp. when the shortened hŭswĭf began to lose caste, through its depreciatory sense [hussy]. But many still pronounce huswif, hussif in Sense 1, even when they write housewife.
The connection between hussy and housewife has long been lost, spelling pronunciation has reinforced what was once a dialectal form, and the calling itself has “lost caste”; so people encounter the word today mostly in writing and pronounce it the way it looks — as they do other words, such as grindstone and those nautical terms from the Age of Sail which Peter Shor mentions.
As for the transferred sense of housewife as a small case — this was originally a first-aid kit for spot repairs carried by the housewife herself:
To bring whatever he had to say, into so small a compass that ... it might be rolled up in my mother's housewife. —Sterne, Tristram Shandy