This paper presents the surface modification of WC-Co alloy with the use of aluminum and silicon powder in wire electric discharge machining (WEDM) process. A separate attachment with the stirrer is used to mix the metal powder in the dielectric, which is further supplied by a pump at the workplace continuously. The effects of different process parameters like peak current, pulse on-time, pulse off-time and servo-voltage are investigated on the material transfer, crack formation and white-layer formation with the help of Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analysis. It was observed that silicon powder enhances the surface quality (4 mu m white layer) compared with aluminum (6 mu m white layer) powder. The white-layer thickness without the use of metal powder was around 14 mu m. The cracks density after the addition powders reduces significantly.