kp, I'd imagine from the added info that a perimeter drain tile was not installed, just the sump pit. Unfortunately, there's evidently not a clear enough sand bed below the floor to conduct all the water to the sump fast enough.
Ideally, you would need to have the floor removed around the perimeter to install a drain tile. To avoid this, if it's practical you could install a second sump near the affected area. Another option is a water channelling system, which can be installed next to the exterior walls. It in effect creates a "gutter" a few inches wide on the floor right next to the wall. This will channel the water around the room to the sump. The channel system would be a control method with no concrete work involved. Since you say the water only occassionally is a problem, this should be an adequate method of repair for the purpose.