Problems of fluid-structure interaction with free surface flow and multi-body interactions are highly nonlinear and complex phenomena, which is challenging for computational modeling and simulation. In the presence of contact or collision between solids, numerical modeling to detect collision and prevent penetration between bodies is required. The objective of this work is to study a numerical model for solid-solid contact and/or collision, based on contact mechanics theories, to reproduce the macroscopic properties of the multi-body interactions in Moving Particle Simulation (MPS) method. MPS is a fully Lagrangian meshfree particle-based approach that is suitable for the modeling complex geometries with large displacements and deformation, including free surface flow with fragmentation and merging and interaction of fluid with multi-bodies. Analytical results are used to perform the calibration of the numerical friction coefficient. The model is applied to a case of free solid transport in free surface flow, modeled as a 3D experimental dam breaking event, in which free solids interact each other and fixed walls. The numerical results from MPS are compared with numerical and experimental results.