<p>Material Extrusion (MEX) is one of the most popular methods used for 3-D printed polymer-based functional parts; however, the possibility of limited wear resistance coupled with frictional behaviour is an issue with many of these parts. The effect of type of nano-filler, filler concentration, quality of dispersion and MEX process parameters on the tribological properties of polymer nanocomposites prepared with available filaments is critically examined. The focus lies on the bonding of interfaces, the agglomeration behaviour, the formation of transfer films, surface roughness and adhesion of the interlayer. The literature surveyed suggests that the dispersion and concentration of the filler have a significant influence on the tribological performance and that excessive loading of the filler has often led to agglomeration, formation of voids and degradation of the mechanical and wear properties. Raster angle, layer height, infill density and nozzle temperature are important process parameters that can greatly influence the wear resistance of the parts produced, due to their impact on the interlayer bonding and the surface quality. The review reveals ideal range of optimum fillers loadings, but does not show that there is a continuous improvement of performance as the filler content increases, and shows some research gaps in terms of alignment of the filler, long-term tribological evaluation, and predictive modelling of the tribological performance. Multifunctional nanocomposites, standardisation of test methods and data-driven optimization for industrial applications are future research directions.</p>