The protection of steel surfaces against wear is a practical problem far agricultural, mining and manufacturing industries. Commercial processes are available in which a hard tungsten carbides rich steel layer is formed on the surface of carbon steel digging, drilling and gouging tools to improve their wear resistance. The nature of the interaction of the tungsten carbide with the steel matrix is important in determining the wear and corrosion properties of the resulting metal matrix composites(MMC). In the study, WC-12%Co/low carbon steel MMC overlays have been prepared by gas metal arc welding(GMAW) according to size of WC-12%Co grits. The characteristics wear resistance and wear mechanism have been investigated in relation to the experiment conditions each other. After MMC overlay had been tested by rubber wheel abrasion test, it was known that MMC overlay has a excellent wear resistance. Fe$_{6}$W$_{6}$C carbides of matrix in overlays were not important to restrain rubber wheal abrasion wear. Wear loss is proportioned to a applied load according to time. On the case of low load, wear occurred severely in the matrix of overlay more than WC-12%Co grit, on the contrary it is reverse on the case of high load because of fracture of WC-12%Co grits.its.