A dimple is a small depression in the cheeks usually seen prominently when someone smiles. Some people’s dimples can be seen permanently, others when they crease their face up to grin, smile or laugh. They seem to be held in high regard and you can be considered more attractive for having dimples.
A pimple is not something you wish to get rid of quickly. It is an inflamed spot on the skin, often on the face and the bane of teenagers’ lives. Some suffer much more than others from them.
A wimple is an old-fashioned headdress worn by nuns and formerly by some women covering their head and necks.
The only other rhyme for these words seems to be the adjective simple.
Amazingly the poet Alfred Lord Tennyson managed to combine them in a verse of his poem Lilian:
So innocent-arch, so cunning-simple,
From beneath her gathered wimple
Glancing with black-bearded eyes,
Till the lightning laughters dimple
The baby-roses in her cheeks;
Then away she flies.