This study puts forth the synergistic effect of fiber concentration and maleic anhydride-grafted polyethylene (PE-g-MA) compatibilization on the abrasive wear properties of high-density polyethylene (HDPE) composites. Composites including carbon, basalt, jute and coconut short fibers with different weight ratios were processed by melt blending and then tested by using a pin-on-disc abrasive wear tester in dry sliding conditions. The test rig was also equipped with a vacuum system, for the first time, to promote two-body abrasive wear of the composites by reducing the wear debris which may be trapped in the wear track and alter the wear properties. In addition, fiber and coupling agent concentrations and test parameters were investigated using L16 full-factorial experimental design and the relationships between these parameters and wear behaviors of the composites were analyzed on the basis of the findings. This work clearly shows that high rigidity obtained by fiber contribution was not beneficial from the abrasive wear resistance point of view, due to repeated plowing effect of the counterpart material under the test conditions. Nevertheless, basalt fiber-reinforced composites showed higher wear resistance than other composites. Except for coconut fibers, PE-g-MA exhibited good miscibility between fibers and matrix, and thus an enhancing effect on the hardness values, and also wear resistance of the samples. Briefly, the rigidity and miscibility of the composites were found in balance for optimum wear rates.