A model of a novel 1–3-type composite containing two ferroelectric components is put forward. In this composite, ferroelectric single crystal (SC) rods and ferroelectric ceramic rods are distributed in a polymer matrix. For a lead-free 1–1–3 composite based on domain-engineered [Li_x(K1−yNa_y)1−x](Nb1−zTa_z)O₃:Mn SC, effective piezoelectric coefficients d3j∗ and g3j∗ and energy-harvesting figures of merit (FOMs) d3j∗g3j∗ are studied taking an active influence of the ferroelectric components into account. In a new m–mc diagram, regions of volume fractions of SC (m) and ceramic (mc) are determined where FOM d33∗g33∗ changes from 6⋅10−11 to 9⋅10−11 Pa−1. Effective parameters of the 1–1–3 and related 1–0–3 composites are compared, and consistency is shown. The large longitudinal piezoelectric coefficient g33∗ and FOM d33∗g33∗ of the lead-free 1–1–3 composite are to be of interest in piezoelectric sensorics and energy harvesting.