You could try spraying bitter apple on your shoes. You can find it at almost any pet store.

You might want to address the root cause as well - dogs that chew on shoes are probably teething or bored (or both).

Make sure the dog has enough toys that he knows are his. Make sure the toys are varied, and that you change them up every so often. It can't hurt to have toys with varied textures - soft ones, ones made from rope, hard ones, etc.

If you catch your dog chewing on anything it's not supposed to, startle the dog with a loud clap or a loud "NO", and then take the item away. Give the dog something it is allowed to have and praise it.