More or less, it's as Risvertasashi stated. Sacred Prism will cancel Asylum and vice versa in the same way that Sacred Soil cancels Shadow Flare, and vice versa. Of course, if you don't PvP it won't affect you much. Now if they ever add more ground AoE support/recovery/damage abilities to WHM in the future, they will most likely also cancel each other out.

That being said, if two different people cast it, then they can overlap. All ground target abilities work with other abilities as long as different people cast them. You can have Sacred Soil from a SCH, Asylum from a WHM, and Shadow Flare from a SMN all going at the same time on the tank and enemy.