Insulated winding wires and associated methods for forming winding wires are described. A winding wire may include a conductor and insulation formed around the conductor. The insulation may provide a partial discharge inception voltage greater than approximately 1,000 volts and a dielectric strength greater than approximately 10,000 volts. Additionally, the insulation may be capable of withstanding a continuous operating temperature of approximately 220° C without degradation. The insulation may include at least one base layer formed around an outer periphery of the conductor, and an extruded thermoplastic layer formed around the base layer. The extruded layer may include at least one of polyetheretherketone (PEEK) or polyaryletherketone (PAEK).