A slip component for a downhole tool has a bearing surface hard surface treated. The slip component, which can be a slip or other component of a slip mechanism used on a packer, bridge plug, or other downhole tool, is composed of a metallic base material such as magnesium, aluminum, an aluminum alloy, or a magnesium alloy. To hard surface treat the slip component, at least the bearing surface is positioned relative to an electro sparking apparatus. Using the electrosparking apparatus, an external layer is bonded at least on the bearing. In a further embodiment, an intermediate layer can be first bonded onto at least the bearing surface by ion sputtering an intermediate material onto the metallic base material of the slip component. Then, an external layer can be bonded at least on the intermediate layer by electrospark deposition.