A refrigerant compressor includes a magnetic bearing assembly including insulation for the coils and lamination stack of the assembly. The lamination stack includes coil apertures extending axially between opposed axial faces. An insert partially extends into a first coil aperture to prevent direct contact between first and second coils. The insert includes a first leg extending into a slot formed in the lamination stack and a second leg radially spaced-apart from the first leg with the second leg extending axially into the first coil aperture. An annular cover having first and second legs extends into respective slots and apertures of the lamination stack. A second annular cover is provided on the opposite face of the coils that is connected to free ends of the second legs. The lamination stack and coils are coated with an insulative material such as epoxy.