I believe an insurance company is only allowed to deduct for wear and tear if you are claiming on your insurance, where it is their policy holders fault they have to provide a replacement for you, as it is not possible for them to get something with identical wear to the one damaged they have to replace with new
I believe you may have got that the wrong way round... if you are claiming off your own insurance policy, the cover (contract) is normally 'new for old', therefore, your own insurer will replace with new... unless the cover does allow for wear & tear of course. fwiw, you probably wouldn't be able to claim for the undamaged wheel as policies normally have a 'matching' exclusion and will only pay for anything that is actually 'damaged or loss'.
You have no contract with a third party insurer, therefore, they can attempt to negotiate a deduction for wear & tear or anything else they can think of. If it's a relatively new bike, their arguments for wear & tear will be somewhat diluted. Remember, it's a negotiation and not set in stone so negotiate hard and threaten Court action if needed... it's not in their interest to go to Court as legal fees will probably far outweigh the claim!
Some insurers will argue you down to the last penny but others may just pay out to get rid of you.
If it goes insurance route, or any route, stick to your guns - no way would I accept different wheels.
The third party's insurer will argue that you're already getting a brand new wheel, which is probably better than the damaged one... so you're already in a better position than before the accident. They will not pay for vanity I'm afraid. B)
Isn't it possible to get the exact same replacement wheel, so that it does match?... although one would be slightly worn/old

but the other would be new.
Just my tuppence worth!