In this work the surface of ductile iron is hardened by a tungsten carbide (WC) layer. The inserted layer is obtained by pouring liquid cast iron on a mixture formed by WC particles (with an average diameter of 6 micrometers) and sodium silicate (acting as a binder). Results show that a sound inserted layer with 2.5mm thickness was produced; the layer is compact, the interstices between particles (with dimensions close to some tenth micrometer) are filled with base metal and the continuity between the WC particles and the base metal is ensured by growth of tungsten rich carbides from the WC particles into the metallic matrix. The surface hardness of the inserted layer achieves Fig.s higher than 500VHN/4.9N.