Term 'socialism' is used very often by Koreans from the North. No one in North Korea would try to correct you if you said that their country is a socialist country. I dare to say that they use word 'socialism' more often than 'Juche'.
And it is not true that the Soviets didn't support them. It is true, that unlike any other country of the Eastern Bloc, North Korea was free from direct influences of Soviet Union. They managed to loosen diplomatic and political ties somewhere in the 1960's (quite notably, concerning that everyone in the Korean government was appointed directly by a Soviet ambassador some 15 years prior). Nonetheless, Russians were sending them tons of stuff (grain, machinery, vehicles and other products) for free until the collapse of the SU, because they feared that North Korea would ally with China (China and Soviet Union, despite being both communist, were quite hostile towards each other). Long story short, China and SU were trying to drag NK into their spheres of influence, and Koreans were profitting tremendously on that, while not giving anything in return nor allying with anyone, diverging onto their own political and social path instead.
Today, North Korea and China are on somewhat friendly terms (not as friendly as most would think), but only since recently.