A process is provided for overmolding an insert or substrate with non-oriented thermoplastic fibers present in an amount that allows them to thermally bond in the presence of non-oriented filler fibers. The thermoplastic fiber fusion retains the filler fibers within the insert upon cooling. The filler fibers are selected to modify the properties of the insert and an overmolded article formed with the insert therein. Such overmolded articles are used in applications including vehicle components such as automotive interior light bases, posts, undercar components, cross members, chassis components, and frame components; architectural components such as home door interiors, sound damping panels, and weather resistant wood replacement. Articles formed with the inventive process yield weight reductions compared to conventional insert overmoldings, along with low scrap generation, process flexibility with respect to part shape and fiber material. Improved recyclability and reduce costs are realized with the inclusion of natural fiber fillers.