The tribological performance of the EUG/NR composites was significantly enhanced by the EUG addition, especially the wear resistance. High-speed friction tests, morphological observations, and related simulations were performed to reveal the strong coupling relationship between the molecular structure, mechanical properties, tribological performance, contact conditions, and wear mechanisms. Low COF, intense friction vibration, and low wear rate were presented by EUG-enhanced mechanical properties, which limited frictional deformation. The wear loss of the recommended 20/80 EUG/NR composite was reduced by 4.4% compared to pure NR. The corresponding COF was decreased by 10.3%. Structural strength and ductility were enhanced and reduced by high crosslinking densities, mono-, and disulfide bonds. This work explains the enhancement mechanism of EUG and provides insight into improving wear resistance.