Composing rhymes with:
decomposing, decomposing, decomposing, imposing, reimposing, decomposing, disposing, exposing, imposing, juxtaposing, opposing, overexposing, posing, predisposing, proposing, reimposing, supposing
Composing sounds like:
campaign's, campaigning, campaigns, campesinos, canvassing, champagnes, confessing, confessions, confusing, confusions