The results of experiments on the study of plasma compression of nested wire arrays of mixed composition and the generation of powerful pulses of soft x-ray radiation (SXR), carried out on a pulse power facility Angara-5-1 at a current level of up to 3 MA, are presented. Based on the latest experimental data on the intensity of plasma formation of various substances (in μg(cm2 ns)−1) (Mitrofanov et al 2020 Plasma Phys. Rep.46 1150–80) and on the features of the dynamics of plasma compression in nested arrays (Mitrofanov et al 2018 Plasma Phys. Rep.44 203–35), a nested wire array design has been developed which makes it possible to obtain a high peak SXR power in comparison with the known designs of single and nested tungsten wire arrays. During the implosion of nested arrays of mixed composition, consisting of plastic fibers and tungsten wires, shorter and more powerful SXR pulses were obtained with a maximum peak power PSXRmax∼ 10 TW with a full width at half maximum (FWHM) duration of ∼5 ns compared to the parameters of SXR pulses upon compression of single tungsten arrays: PSXRmax∼ 5 TW and FWHM ∼ 10 ns. Thus, under the conditions of our experiments, we have shown the possibility of a twofold increase in the peak SXR power during compression of nested arrays by optimizing their design.