In a non-mainstream theory, the protons are made of electrons and positrons i.e. a nucleus of positrons orbited by electrons with the proton having an excess of one positron and the neutron having equal numbers of electrons and positrons. The theory also claims that the strong and weak interactions are manifestations of the electromagnetic force.
Neutrons and protons would combine to form nuclei with their outer electrons forming nuclear orbitals just like the outer electrons of atoms forming molecular orbitals. The free neutron would be different from the proton and is found to be decay into a proton, an electron and an anti-neutrino. This is understandable because the neutron is like a proton with an extra electron; it just loses that electron to become a proton.
In the combined state, the neutron's extra electron freely rotates within the nuclear orbital leaving the neutron indistinguishable from the proton which is the epitome of stability. This better explains the stability of the neutron in the nucleus.
There's a phenomenon called electron capture where a shell electron is captured by the nucleus. This is easier to understand with the new theory because nuclear orbitals are populated by electrons which means the shell electron would feel at home within the nuclear orbital. But the main reason why a shell electron gets pulled into the nucleus is because there's sufficient positive charge to overcome the repulsive charges between the nuclear electrons and the shell electrons.
Another way of getting rid of the positive charge is to eject one of the positrons in either the neutron or the proton because they look alike anyway.
Check out The One Force of Nature; a free download that explains an alternative theory of science.