  The QCD hardness scale for secondary particles ($h$) production in
semi-inclusive deep inelastic scattering (DIS), $e p \to e' X h$, gradually
decreases from $Q^{2}$, the photon virtuality which determines the hard scale
in the virtual photon (current) fragmentation region to a soft, hadronic, scale
in the proton fragmentation region. This suggests similarity of the inclusive
spectra of leading protons and neutrons, $h=p,n$, in high energy hadron-proton
and virtual photon-proton collisions. We explore this similarity extending to
the DIS regime the nonperturbative peripheral mechanisms of inelastic
scattering traditionally used in hadronic interactions to explain fast nucleons
production. While the production of leading neutrons is known to be exhausted
by DIS off charged pions, the production of leading protons by DIS off neutral
pions must be supplemented by a substantial contribution from isoscalar reggeon
($f_{0}$) exchange extrapolated down to moderate values of $x_{L}$. We comment
on the $x$ and $Q^{2}$ dependence of leading proton production as a probe of a
universal pattern of the $x,Q^{2}$ evolution of the nucleon and meson (reggeon)
structure functions at small $x$.
