You might want to get some used wheels, with more spokes and a wider rim profile, and of course wider tires. You can of course use different setups, and have the rear wheel be stronger, wider etc.
I hate to ask but when you got the Felt from the store, did you check the tension of the wheels? If the shop just took them out of the box and assembled the bike, they may not have been properly tensioned, which would make them more suseptable to damage.