This work comparatively evaluates the effect of nano-SiO2 (at 2 and 3 wt%), rice husk and bagasse ash (at 5 and 10 wt%) on the wear resistance and friction coefficient of HDPE (high-density polyethylene)/lignocellulosic fiber composites. Rice husk and bagasse fibers at 50% by weight contents were mixed with HDPE and 2% maleic anhydride-grafted polyethylene as compatibilizer. SEM images showed a fairly appropriate connection between the polymer matrix and fillers. We found that the fillers improve the wear resistance, and the effect of nano-SiO2 is more pronounced. The rice husk ash showed a better performance compared to the bagasse ash, probably due to greater SiO2 content measured by X-ray fluorescence spectrometry. In contrast to nano-SiO2, both ashes had a reducing effect on other mechanical strengths (Izod impact resistance, modulus of elasticity and modulus of rupture). All fillers remarkably increased the water absorption and thickness swelling. The water uptake of composites increased after wear.