Methods and apparatuses for reducing electrical arcing currents or electron emissions to a wafer or to components in a plasma chamber are provided. An insert for use in a process chamber having a wafer support is disclosed. The insert comprises a composite member formed of a first material, such as for example, silicon, and a second material, such as for example, SiO2, having a greater electrical impedance than the first material. The composite member has a surface which is adapted to be disposed adjacent to the wafer support, and which is made of the second material. In one aspect, the process chamber further has an outer member adapted to surround the wafer support. The composite member has a surface which is adapted to be disposed adjacent to the outer member and which is made of the second material. In another aspect, the composite member has a surface which is adapted to be disposed adjacent to a semiconductor wafer and which is made of the second material.