There may be a reason why this particular resource is more common than Tungsten. It has been stated throughout the franchise that humanity is running incredibly low on resources, prompting Planet Cracking. As a natural resource, tungsten would be very hard to mass-produce, in contrast to a resource like Somatic Gel, which can be mass-produced to yield a large amount.
"Soma" is used in System Shock II, one of the inspirations of Dead Space, to connotate a psychic power that affects the user's health. So "Somatic Gel" means "A semisolid that affects the user's health."