Friction and wear of polyetheretherketone (PEEK) was simulated taking into account the development of triboxidation and scuffing processes induced by the work of friction forces and plastic deformation. From the solid mechanics point of view, these effects were accounted in the form of friction coefficient variation. It took place when the temperature has exceeded a threshold value at the contact between a steel counterpart and a polymer sample (due to friction heating). Simulation of friction and wear processes was carried out by solving a contact and heat conduction problems for a computational domain. The latter corresponded to conditions of experimental wear tests conducted by “block-on-ring” scheme. The effect of friction coefficient variation at scuffing on volumetric wear rate of PEEK and PEEK-based carbon fiber reinforced composites has been established. The effect of carbon fiber length on wear resistance of PEEK-based composites was analyzed. It was shown that when scuffing is taken into account, the calculated value of wear intensity of PEEK-based composites increases. It was shown that loading with long carbon fibers ensured reduction of the wearing both without and with taking the scuffing effect into account.