Webb's rhymes with:
webbs, webs, celebs, debs, ebbs, krebbs, krebs, tebbs, webbs, webs
Webb's sounds like:
wabash, wabash's, waives, waves, weaves, webbs, webs, weeps, whipkey, whipps, whips, whipsaw, whoops, wiebke, wiebusch, wife's, wipes, wives, wives', wobig, wops