The interaction between a cermet cladding plate part and a homogeneous cylindrical part under wear condition is simplified as a plain strain contact problem. Based on Hertz contact theory, the theoretical model of the maximum shear stress in the cladding part is built; an example and its finite element analyses (FEA) are given. Theoretical results well coincide with those of the FEA. Both results show that, with the increase of the cladding thickness, the maximum shear stress decreases, its position shifts toward the clad surface. The effects of the wear load and the properties of the frictional materials on the maximum shear stress are also studied. The research results have great significances to the design of cladding parts under wear condition.