How to minimize wear on pants
The obvious answer would be to get some Cycling Jeans, i.e. jeans specifically designed for cycling in. These have reinforcement and stretch in the right places and often have other features such as deep pockets, a loop to carry a small lock and reflective strips.

Levi, Rapha, Muxu and Swrve all make cycling jeans, so there's a fair amount of choice.