  In this work we consider the scalar field model with a false vacuum proposed
by A. T. Avelar, D. Bazeia, L. Losano and R. Menezes, Eur. Phys. J. C 55,
133-143 (2008). The model depends on a parameter $s>0$. The model has unstable
nontopological lump solutions with a bell shape for small $s$, acquiring a flat
plateau around the maximum for large $s$. For $s\to\infty$ the $\phi^4$ model
is recovered. We show that for $s\gtrsim 2$ the lump is metastable with the
only negative mode very close to zero. Metastable lumps can propagate and
survive long enough to produce dynamical effects. Due to their simplicity, they
can be an alternative to the procedure of stabilization which requires, for
instance, a complex scalar field to construct nontopological solitons. We study
lump-lump collisions in this model, describing the main characteristics of the
scattering products at their dependence on $s$ and the initial velocity modulus
of each lump.
