A cemented carbide body includes WC in a metallic binder phase. The cemented carbide body has a bulk portion and a surface portion. The grain size of the WC in the surface portion is smaller than the grain size in the bulk portion of the body and this gives an increased surface hardness and an increased wear resistance. The median grain thickness, tg, of WC in the surface portion is 20-300 nm and the average grain size in the bulk portion is 0.5-8 μm. A method of surface hardening a cemented carbide body is also provided.