Silene compacta
There is a taxonomic confusion with the name of this plant. GBIF (Global Biodiversity Information Facility) says that Silene compacta is a synonym of Actocion compactum while The World Flora Online says Silene compacta is the accepted name.
It is a beautiful plant, the closely packed florets reminding you of Silene acaulis (Moss Campion) and it seemed to be a magnet for insect life too. According to the distribution maps of GBIF, it is mostly found in the Caucasus mountains, the Russian Black Sea coastal area and dotted around in eastern Greece.
The insect is similar to Trichodes nuttalli (Red-Blue Chequered Beetle) found in the north American Continent but not usually here. I'm not an entomologist so this is just a guess based on colour and morphology.