We study the three-dimensional bosonic t-J model, that is, the t-J model of "bosonic electrons" at finite temperatures. This model describes a system of an isotropic antiferromagnet with doped bosonic holes and is closely related to systems of two-component bosons in an optical lattice. The bosonic "electron" operator B(x sigma) at the site x with a two-component spin sigma(= 1,2) is treated as a hard-core boson operator and represented by a composite of two slave particles: a spinon described by a Schwinger boson (CP(1) boson) z(x sigma) and a holon described by a hard-core-boson field phi(x) as B(x sigma) = phi(dagger)(x)z(x sigma) By means of Monte Carlo simulations of this bosonic t-J model, we study its phase structure and the possible phenomena like appearance of antiferromagnetic long-range order, Bose-Einstein condensation, phase separation, etc. Obtained results show that the bosonic t-J model has a phase diagram that suggests some interesting implications for high-temperature superconducting materials.