  Long lifetimes of spatially indirect excitons (IXs), also known as interlayer
excitons, allow implementing both quantum exciton systems and long-range
exciton transport. Van der Waals heterostructures (HS) composed of atomically
thin layers of transition-metal dichalcogenides (TMD) offer the opportunity to
explore IXs in moir\'e superlattices. The moir\'e IXs in TMD HS form the
materials platform for exploring the Bose-Hubbard physics and superfluid and
insulating phases in periodic potentials. IX transport in TMD HS was
intensively studied and diffusive IX transport with $1/e$ decay distances
$d_{1/e}$ up to $\sim 3$ $\mu$m was realized. In this work, we present in
MoSe$_2$/WSe$_2$ HS the IX long-range transport with $d_{1/e}$ exceeding 100
$\mu$m and diverging at the optical excitation resonant to spatially direct
excitons. The IX long-range transport vanishes at high temperatures. With
increasing IX density, IX localization, then IX long-range transport, and then
IX reentrant localization is observed. The results are in qualitative agreement
with the Bose-Hubbard theory of bosons in periodic potentials predicting
superfluid at $N \sim 1/2$ and insulating at $N \sim 0$ and $N \sim 1$ phases
for the number of bosons per site of the periodic potential $N$.
